HELP! New grower wondering if this is light burn or nutrient deficiency?

[SH4D0W3D]

Hi everyone, new grower here. First time doing this.
I've been looking around the site a bunch, but I cannot clearly identify my plant's problem.

I've started noticing these pale spots in week 4 (from planting) :



At first I thought this could be light burn. I am using LED lights which were positioned around 4 to 5 inches away from canopy, so I increased the distance from the light source to 11 inches.

But then I am seeing this in week 5 :



Anyone could tell me if this really is light burn?
What boggles my mind is that since I experienced tall stem seedling and slow growth, I initially thought that it was not having enough light to begin with.
Here it is in the first week :




Here is more information that could prove useful :
Strain : Feminized Autoflower Banana Kush
LED Light (x2) : https://www.amazon.ca/gp/product/B082YWKWGH
Light schedule : 18/6
Location : In a 3x4 closet covered with Mylar film. There is another 2 week younger plant present as well (Feminized Autoflower Gelato).
Soil : Schultz Potting Soil Plus (0.08-0.12-0.08)
Water : Bottled water, reverse osmosis.

Thanks in advance!

[Holden90]

If it was a nitrogen deficiency I would expect to see purple stems, it looks similar to an Iron deficiency combined with high soil ph.
I use the Canna website deficiency guide, I only use their products so it works for me.
do you have a soil tester to check moisture levels and ph?

[gbauto]

Plants are starving for nutrients.
FEED THEM

[Holden90]

For sure

[HobbitGDF]

How big of buds do you think them lights will make?
I think you also might want to upgrade them.
i cant find the real watts they put out. But i dont think it's much. Just my opinion. But at 5 weeks it's time for some nutrients.

[Holden90]

What you said, I didn't check them out initially. Sorry mate but I did burst out laughing when I saw them. Put your plants by a window, it will be better than those lights.... and start bringing the feed up, that soil looked very dry

[SH4D0W3D]

Point taken lol! Used the LUX app on Android to measure light and, well. yeah. Definitely can't be light burn with that reading (less than 200FC) LOL!
I had 2x 6500k 23W CFLs laying around and installed them. Got a better reading now (600+FC), but I definitely need more.

[SH4D0W3D]

How big of buds do you think them lights will make?
I think you also might want to upgrade them.
i cant find the real watts they put out. But i dont think it's much. Just my opinion. But at 5 weeks it's time for some nutrients.

Thanks for the tip. I will make the complete switch to a few 6500K CFLs, its the fastest change I can make right now. I was afraid it was light burn, that's why I hesitating to make the switch.
Being the first time growing anything (never even a normal house plant lol)

I will investigate more on nutrients too, I guess the nutrients already contained in the potting soil isn't enough?

[Paracelsus]

Feed the soil good nutrients if you want a healthy plant.

[Rwise]

What I see is a root issue, what is the PH?

[SH4D0W3D]

I have yet to do a PH test. I will do so today, hopefully I'll do this right; I have a hard time reading ph test strips... Wish there was a cure to colorblindness.

[PLreef]

I think you have some big ph fluctuations going on. What ph are you feeding and what is the ph at the root zone? How are you testing ph?
if there's anything this site and its members taught me is to stay on top of ph. Its one of the most important parts of growing.

[Rwise]

PH issues are the number one reason for problems in the grows and the most ask questions are around PH issues right here on this site.

[PLreef]

I definitely understand. I believe your the one that originally taught me about ph stability and its importance to the grow.

[SH4D0W3D]

I have not tested PH yet. Good point. I will go buy a quick soil test at local hardware store to check it. Thanks for the tip

[smoorman]

If you're using ro water you may need to supplement with cal-mag. I think this may help with existing available nutrients.

[SH4D0W3D]

Thanks for the tip. I may switch to tap water as I read that RO water is prone to PH fluctuations and requires cal-mag supplement like you said. I will test ph of my tap water first though

[SH4D0W3D]

I would like to say a big thank you to all who responded! You guys put me on the right track for sure.

Here's an update on what I did:

• Removed my laughable LED lights and installed 6x 6500k 23W CFLs.
  • I am now getting a 2000+ FC reading at plant canopy with the new setup, as opposed to a less-than 300FC with the LEDs.
  • I could potentially move the lights closer to the plants and get the 2500FC sweet spot, but I am playing it cautious for now and see how well the plants respond to this change just in case the LUX app might be inaccurate.
• Bought nutrients and administered the first dose.
  • Its only been a little over 18 hours since the feed and the plant seems to be doing better already.
    I can't be sure, but I think I saw it do the happy dance from the corner of my eye while I was watering the second plant lol!
• Purchased and performed PH test.
  • I was not able to find a digital one in local stores and couldn't get a decent one with next-day shipping on amazon. (ordered one, will get it in a few days)
  • Purchased a single use liquid check for emergency verification... can't tell the PH level very accurately, but it doesn't seem to be critical; then again, I'm colorblind and I've always had issues comparing liquids to printed charts. Let me know if I'm out of whack. (pic included further down).

Here's my new setup :




Here's the nutrients I purchased :




Here's the result of the soil PH test :




Moisture reading, 18 hours after feed :

[Holden90]

PH looks in the 6 range, for soil that is good. It should be pretty stable and if it starts to creep up use a water flush. It still going up then use a PH - solution. what we are trying to do is prevent a build up of salts in the soil as water is taken up.
From what I have experienced with watering a potted plant, that wet line hits the lower quarter then time for a drink. Feeding is done 2-3 times a week, water between feeds if she gets dry.
Well done on the bounce back, and the GWE community is pretty helpful to us all.